feat: add shareable URL functionality with copy-to-clipboard button

Implement URL parameter serialization for sharing RDAP queries with
deep linking support. Add ShareButton component with clipboard
integration and visual feedback. Queries are automatically restored
from URL parameters on page load, enabling direct navigation to
specific RDAP lookups.

src/components/ShareButton.tsx

@@ -0,0 +1,66 @@
+import type { FunctionComponent } from "react";
+import { useState, useCallback, useEffect } from "react";
+import { Link2Icon, CheckIcon } from "@radix-ui/react-icons";
+import { IconButton, Tooltip } from "@radix-ui/themes";
+
+export type ShareButtonProps = {
+	/**
+	 * The URL to copy when the button is clicked
+	 */
+	url: string;
+	/**
+	 * Button size (1, 2, or 3)
+	 */
+	size?: "1" | "2" | "3";
+	/**
+	 * Button variant
+	 */
+	variant?: "classic" | "solid" | "soft" | "surface" | "outline" | "ghost";
+};
+
+const ShareButton: FunctionComponent<ShareButtonProps> = ({
+	url,
+	size = "1",
+	variant = "ghost",
+}) => {
+	const [copied, setCopied] = useState(false);
+
+	// Reset copied state after 2 seconds
+	useEffect(() => {
+		if (copied) {
+			const timer = setTimeout(() => setCopied(false), 2000);
+			return () => clearTimeout(timer);
+		}
+	}, [copied]);
+
+	const handleShare = useCallback(() => {
+		navigator.clipboard.writeText(url).then(
+			() => {
+				setCopied(true);
+			},
+			(err) => {
+				if (err instanceof Error) {
+					console.error(`Failed to copy URL to clipboard: ${err.toString()}`);
+				} else {
+					console.error("Failed to copy URL to clipboard.");
+				}
+			}
+		);
+	}, [url]);
+
+	return (
+		<Tooltip content={copied ? "Copied!" : "Copy shareable link"}>
+			<IconButton
+				size={size}
+				variant={variant}
+				color={copied ? "green" : "gray"}
+				aria-label="Copy shareable link"
+				onClick={handleShare}
+			>
+				{copied ? <CheckIcon /> : <Link2Icon />}
+			</IconButton>
+		</Tooltip>
+	);
+};
+
+export default ShareButton;